weston



4 Sheets- Sheet 1.

E. WESTON.

SHUNTING ATTACHMENT FOR ELECTRIC ARC LAMPS: No. 264,984.

(No Model Patented Sept. 26, 1882:

(No Model.) 4 Sheets-Sheet 2. B. WESTON.

SHUNTING ATTACHMENT FOR ELEGTRIG ARC LAMPS.

No. 264,984. atented Sept-26, 1882.

(No Model.) 4 Sheets--Shaet 3.

E. WESTON.

SHUNTING ATTACHMENT EOE ELECTRIC ARG LAMPS. No. 264,984. Patented Sept. 26, 1882.

Inventor.

N. PETERS Fhotn-Llthogrdphcr, Wnhingtan. D. (Iv

(No Model.) 4 Sheets-Sheet 4.

E. WESTON.

SHUNTING ATTAOHMENT FOR ELECTRIC ARG LAMBS. I No. 264,984. Patented Sept. 26,1882.

F95. Fly 6 UNITED STATES PATENT OFFIQE.

EDTVARD W'ESTON, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE UNITED STATES ELECTRIC LIGHTING COMPANY, OF NElV YORK, N. Y.

SHUNTING ATTACHMENT FOR ELECTRIC-ARC LAMPS.

SPECIFICATION forming part of Letters Patent No. 264,984, dated September 26, 188.2.

Application filed April 27, 1882.

To all whom it may concern:

Belt known that I, EDWARD WEs'roN, of Newark, in the county of Essex and State of New Jersey, have invented certain new and usefulImprovementsinShuntingAttachments for Electric-Arc Lamps,of which the following is a specification, reference being had to the accompanying drawings, forming a part of the same.

In electric-arc lamps it may occur, through derangement of the feed-controlling mechanism or through the failure of some of the parts to perform their allotted functions, that the upper or movable carbon is not properly fed I 5 toward the other. As a result, an arc of abnormal length is formed between the two carbon points, which in a comparatively short time may assume such proportions as to endanger thelamp. Such occurrences,although extremely rare, even in circuits containing large numbers of lamps, where currents of very high tension are required, are nevertheless possible, and to guard against any possible injury to the lamps from this source I design employing in connection with each lamp an attachment in the nature of a safety de vice, which shall operate on the elongation of the are beyond the limits of safety to shunt the current around the lamp. Heretofore this.

object has been accomplished by the employmentof electromagnetic devices or their equivalents in shunt or derived circuits around the lamps; but inasmuch as the diversion of current from the main or lamp circuit through 5 the shunts often results in the burning of the coils of fine wire contained therein, I have de vised an apparatus the operation of which is made to depend on causes in a certain sense independent of the electrical conditions of the circuit. Under normal conditions the arc is practically confined to the space between the two carbons. When the arc, on the other hand, becomes unduly elongated, it leaves this space and branches out and up at the same time, ex-

4 5 hibiting a tendency to travel around the carbons. In my present invention 1 take advantage of this phenomenon of displacement to operate a cut-out. To this end I employ a normally-open branch circuit around the are, containing or not, as may be determined by preference or the necessities of the case, a resist- (No model.)

ance. To close this circuit when the arc has become so distorted and has reached such a length as to endanger the lamp, I use a safetyswitch of proper character, which will be brought into operation by the heat developed by such an arc.

The special character of the safety device may be greatly varied, and among the many ways in which the desired end is attained are the following: The contact-surfaces of a mechanical circuit-closer may be held apart by a strip of combustible or easilyfused substance, and this arranged at a point in the vicinity of the are where, upon an undue elongation of the same, the heat developed will ignite or fuse the substance which keeps the circuit open and permit the points of contact to come together. The point at which the above device is placed should, however, be sufficiently remote from the arc to prevent the heat under normal conditions from afi'ecting it. Another means of accomplishing this result is by the employment of an independent circuit containing a thermal pile and an electro-magnet. The pile is placed where only the heat of a very long are will cause it to generate sufficient current to energize its magnet. TVith the magnet is arranged a circuit-closer in a severed branch about the arc. Still another device for the same purpose consists ofa switch in the open branch circuit, arranged to be closed by the movement of a metallic thermometer or pyrometer placed with reference to the arc in a manner which will be understood from the above. These several forms of switch, being all operated by force due to the application of heat, I term thermodynamic switches or safety devices.

The first of the above-described means of carrying out the invention I have illustrated in detail, and the nature of the invention and manner of applying the same will be described more particularly with reference to it.

In the drawings, Figure 1 represents a sin- 5 gle lamp complete with a safety-switch applied. Fig. 2 is a double lamp represented in a similar manner with a safety-switch. Fig.

3 is an interior view, partly in section, showing the arrangement of parts and circuits required in applying the invention. Fig. 4 is a detail of the safety-switch shown in the previous fignres. Fig. 5 is a view of a modified form of safety-switch involving a thermal pile. Fig. 6 is another modification, showing a pyrometer.

Referring to Figs. 1 to 4, inclusive, the cross-bar A of the lamp is perforated at a point, say, an inch and a half from the point through which passes the carbon-holder B. In this perforation is inserted a tube or sleeve of insulating substance, 0, having a wide flange, 0. Through the tube 0 is passed a metal rod, D. Over the end of tube 0 is secured by screw-thread or otherwise a metal tube, E, somewhat shorter than rod D. To the end of tube 0 is fixed a ring having ears 0 e, the former bent, as shown in Fig. 3, and split. 0n the end of rod D, projecting beyond the tube E, is a bar, d, held in place by a screw, d, and capable of turning freely on the rod. One end of bar d is split, the other bent up, or provided with a stop, a. A light spring,f, is fixed to rod I) and bears on the stop a, imparting to the bar 61 a tendency to turn and bring stop a in contact with car 6. This movement is prevented by a strip of easily-fused substance 9, which is to be properly secured to the split ends of ear 6 and bar d. Rod D is to be connected with the wire which introduces the current to the lamp, and the tube E is electrically connected by an insulated wire to the negative terminal of the lamp. The length ofrod D and tube E is determined by experiment,and will of course differ according to such circumstances as the limit which it is desired to fix for the length of are or the degree of fusibility-of the strip g.

The fusible substance which I prefer to employ in this device is an alloy composed of tin,

four parts; lead, two parts; cadmium, two parts; bismuth, one part-the above proportions by weight. When a metallic strip is used care must be taken to insulate one end at least from the part to which it is attached, as otherwise it would form a path for the current around the lamp.

It with a device constructed as above set forth the rod D be extended to a point, say, two or three inches from the are at the outset, the desired results will be obtained, for as the negative carbon burns but little the change of position of the arc in a vertical line will not affect the working of the safety device, for by the displacement of the are when it becomes elongated the strip 01 is either enveloped in flame or heated sufficiently to be fused. In either event the stop a and ear 6 are brought into contact and the lamp short-circuited, even though these parts he placed at a distance of several inches from the end of the positive carbon. The fact that the fusible strip is only on one side of the carbons does not materially, if at all, render its fusion less certain, inasmuch as the arc does not remain in the same place, but exhibits a continual tendency to revolve around the carbon points.

It may be stated that the fusible metal may be supplanted by a strip of some combustible The above device may be applied to any ordinary lamp, whether a single lamp or one containing two or. more sets of carbons, the manner of applying the same being shown in Figs. 1 and 2. As to the safety-switch itself, no specific plan of construction'is prescribed, though the form shown is believed to be the most practicable. It is evident that many variations of this special form are possible, two insulated springs, forming the terminals of a severed branch circuit, and a suitable strip or block of fusible substance holding them apart, forming one means of accomplishing the object desired.

-In Fig. 5 is shown a small thermal pile, L, in place of the safety device previously described. This pile is sustained by a tube, L, containing the conductors, at a point with reference to the are which is determined by experiment, and has wires 1 1 leading from its poles to a small elcctro-magnet, M, contained in the casin g of the lamp. With this magnet is arranged a circuit-closer, (represented by the conventional levers and stops in the drawings,) which circuit-closer is so adjusted as to be affected and tripped only by a current of predetermined strength, and then to permanently close the previously-open branch circuit. In Fig. 6 a tube, L, corresponding to.

that shown in the former figure, contains a pivoted rod or trigger, N, which holds up a contact-lever, p, and maintains the branch circuit with which it is connected open. A cir cular metallic case, N, is carried by the tube L, in which case is arranged a spiral spring, S, composed of two or three difierent metals, and arranged, in the manner of the well-known metallic thermometers,with a pointer, P. By the heat of a long are the pointer is brought around against the end of trigger N, and, imparting to'it a slight movement, trips the lever 19 and completes the branch circuit.

Many other modifications of this device are possible, but those described are thought suffivention, and as they have been fully described same exceeded a certain limit. My invention, however, differs from this mainly in the fact that its operation is due primarily to the lengthening; of the are, rather than to a rise of temperature in a normal are, and, secondly, in that the devices which I have described as constituting my invention act to permanently close the circuit about the carbons when an abnormal arc has formed.

Having now described my invention, what I claim is- 1. In an electric lamp, the combination, with the carbon pencils or electrodes, of a normallyopen derived circuit around the lamp, and a thermodynamic safety-switch or shunting device connected therewith, said device being constructed and arranged to be operated upon the displacement of the are, due to the abnormal elongation of the same by the heat developed by the are, and thereby close the derived circuit, as and for the purpose set forth.

2. In an electric lamp, thecombination, with the electrodes, of a normally-open derived circuit, a circuit-closer contained therein, and a safety device such as afusible strip or its equivalent for holding apart the contact-points of the circuit-closer, the said safety device being constructed and so arranged with reference to the position of the are that upon an undue elongation of the same it may cause the contact-points to come together, thereby permanently closing the derived circuit, as set forth.

3. In an electric lamp, the combination,with the electrodes, of a normally-open derived circuit, a spring circuit-closer connected therewith, and a strip or piece of fusible or combustible substance for holding the contact-points of said circuit-closer apart, these parts being so constructed and arranged with reference to the position of the are that upon an undue elongation and displacement of the same the heat will melt or destroy the fusible strip, and thereby close the derived circuit, as described.

In testimony whereof I have hereuntoset my hand this 21st day of April, 1882.

EDWARD WESTON.

Witnesses:

PARKER W. PAGE, W. FRIsBY. 

